Coherent light generators – Particular resonant cavity – Distributed feedback
Reexamination Certificate
1996-12-17
2001-04-03
Arroyo, Teresa M. (Department: 2881)
Coherent light generators
Particular resonant cavity
Distributed feedback
C372S099000, C372S108000, C385S031000, C385S010000, C385S037000
Reexamination Certificate
active
06212216
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to external cavity micro laser apparatus wherein one or more multimode micro lasers (as herein defined) are efficiently coupled directly into the input aperture of an optical fiber or other optical waveguide.
BACKGROUND OF THE INVENTION
As used herein, the term “external cavity micro laser apparatus” means apparatus comprising multi-mode micro laser means (as herein defined) having an external cavity for accomplishing mode selection, mode mixing, frequency selection, pulse shaping, beam take-off, and the like.
As used herein, the term “multi-mode micro laser” (or “multi-mode micro laser means”) is intended to mean lasing devices, typically but not necessarily of semiconductor construction, which are micro-miniature in size with dimensions typically measured in microns, which may produce one-dimensional or two-dimensional coherent, partially coherent or incoherent emissions, and which produce multiple modes each with multiple lasing lobe components. The term is intended to embrace what are today commonly known as “broad area lasers” or “BALs” which may have an aspect ratio of, e.g., 50:1 to 400:1 (slow axis to fast axis ratio). The term encompasses “laser arrays” which comprise a series of spaced coupled or uncoupled emitters—either broad area lasers or standard lasers. The term also includes laser bars which may be up to a few centimeters wide, e.g., which may contain an array of uncoupled BALs, or a two-dimensional stack of such laser bars. Typical broad area lasers have a single broad stripe for increased output power. Laser arrays have individual current stripes, one for each emitter, which may be closely spaced such that there is a strong mutual coupling or interaction between the light generated by the emitters. In practice, a laser array behaves similar to a broad area laser with respect to its modal properties, except that a laser array prefers to oscillate in higher order modes of order N, where N is equal to the number of stripes or emitters. In a working system “N”, for example, might have a value of 10.
An intense need exists for diffraction limited laser sources of several hundred milliwatts of output power for pumping optical fiber amplifiers in communication networks. Commercially available semiconductor lasers are capable of delivering high power, however, the need for an efficient and inexpensive means for coupling the semiconductor laser energy over a few hundred milliwatts into the input aperture of an optical fiber or other optical waveguide has not, prior to this invention, been satisfied.
There are two characteristics of output beams from micro lasers that make single mode fiber coupling inefficient. First, in the slow axis direction (major axis direction of the near field elliptic output beam), micro lasers support multiple transverse modes that are incoherent with respect to each other. Consequently, the output beam cannot be focused with near-diffraction-limited performance in this direction.
Second, the high ellipticity or high aspect ratio of the output beam cross section (typically greater than 1:100 at the near field) results in poor mode matching with the typically circularly symmetric modes of optical fibers.
SUMMARY OF THE INVENTION
In accordance with the present invention, the coherence of the output beam from such micro lasers is dramatically improved to make possible near-diffraction-limited imaging of the output beam into the input aperture of an optical fiber or other optical waveguide. In accordance with an aspect of the invention, means are provided for reshaping the aspect ratio of the output beam such that it conforms more closely to the aspect ratio of the input aperture of the coupled optical waveguide. In accordance with an aspect of the invention, the input aperture is employed as a spatial filter to select desired lasing lobe components of the output beam.
In order to obtain near-diffraction-limited performance in the slow axis direction, either the fundamental mode or a group of phase-locked higher order modes of the micro laser are excited by appropriate optical feedback. To achieve an approximately circularly symmetric spot size that matches the input aperture of the coupled optical waveguide, an appropriately designed coupling optics having an anamorphic component is employed.
REFERENCES:
patent: 4214216 (1980-07-01), Jones, Jr.
patent: 4246548 (1981-01-01), Rutz
patent: 4503541 (1985-03-01), Weller et al.
patent: 4504950 (1985-03-01), AuYeung
patent: 4583226 (1986-04-01), Liou
patent: 4689797 (1987-08-01), Olshansky
patent: 4730325 (1988-03-01), Chow
patent: 4809288 (1989-02-01), Welch et al.
patent: 4852113 (1989-07-01), Botez
patent: 4866724 (1989-09-01), Botez et al.
patent: 4995047 (1991-02-01), Hadley et al.
patent: 4995050 (1991-02-01), Waarts et al.
patent: 5012483 (1991-04-01), Reintjes et al.
patent: 5018831 (1991-05-01), Wyatt et al.
patent: 5027359 (1991-06-01), Leger et al.
patent: 5033054 (1991-07-01), Scifres et al.
patent: 5050180 (1991-09-01), Botez et al.
patent: 5063570 (1991-11-01), Botez et al.
patent: 5163058 (1992-11-01), Farries et al.
patent: 5179548 (1993-01-01), Sandesara
patent: 5272711 (1993-12-01), Mawst et al.
patent: 5297154 (1994-03-01), Heidemann et al.
patent: 5299219 (1994-03-01), Hayakawa
patent: 5319659 (1994-06-01), Hohimer
patent: 5392308 (1995-02-01), Welch et al.
patent: 5430748 (1995-07-01), MacCormack et al.
patent: 5438585 (1995-08-01), Armour et al.
patent: 5485481 (1996-01-01), Ventrudo et al.
patent: 5572542 (1996-11-01), Dixon
PCT International Search Report; PCT/US97/18247, dated Feb. 23, 1998.
Bogatov et al., “Injection Laser with an Unstable Resonator”, Sov. J. Quantum Electron 10(5), May 1980, pp. 620-622.
Chang-Hasnain et al., “Characteristics of the Off-Centered Apertured Mirror External Cavity Laser Array”, Appl. Phys. Lett. 54(6), Feb. 6, 1989, pp. 484-486.
Chang-Hasnain et al., “Diffraction-Limited Emission from a Diode Laser Array in an Apertured Graded-Index Lens External Cavity”, Appl. Phys. Lett. 49(11), Sep. 15, 1986, pp. 614-616.
Chang-Hasnain et al., “High Power with High Efficiency in a Narrow Single-Lobed Beam from a Diode Laser Array in an External Cavity”, Appl. Phys. Lett. 50(21), May 25, 1987, pp. 1465-1467.
D'Amato et al., “Coherent Operations of an Array of Diode Lasers Using a Spatial Filter in a Talbot Cavity”, Appl. Phys. Lett. 55(9), Aug. 28, 1989, pp. 816-818.
Epler et al., “Far-field Supermode Patterns of a Multiple-Stripe Quantum Well Heterostructure Laser Operated (~7330 Å, 300 K) In An External Grating Cavity”, Appl. Phys. Lett. 45(4), Aug. 15, 1984, pp. 406-408.
Goldberg et al., “Injection Locking Characteristics of a 1 W Broad Stripe Laser Diode”, Appl. Phys. Lett. 53(20), Nov. 14, 1988, pp. 1900-1902.
Goldberg et al., “Injection Locking of Coupled-Stripe Diode Laser Arrays”, Appl. Phys. Lett. 46(3), Feb. 1, 1985, pp. 236-238.
Goldberg et al., “Broad-area High-Power Semiconductor Optical Amplifier”, Appl., Phys. Lett. 58(13), Apr. 1, 1991, pp. 1357-1359.
Goldberg et al., “Injection Locking and Single-Mode Fiber Coupling of a 40 Element Laser Diode Array”, Appl. Phys. Lett. 50(24), Jun. 15, 1987, pp. 1713-1715.
Goldberg et al., “Single Lobe Operation of a 40-Element Laser Array in an External Ring Laser Cavity”, Appl. Phys. Lett. 51(12), Sep. 21, 1987, pp. 871-873.
Hohimer et al., “Injection-locking Characteristics of Gain-Guided Diode Laser Arrays with an “On-Chip” Master Laser”, Appl. Phys. Lett. 56(16), Apr. 16, 1990, pp. 1521-1523.
Hohimer et al., “Single-Channel Injection Locking of a Diode-Laser Array with a CW Dye Laser”, Appl. Phys. Lett. 47(12), Dec. 15, 1985, pp. 1244-1246.
Jansen et al., “Coherent Operation of Injection-Locked Monolithic Surface-Emitting Diode Laser Arrays”, Appl. Phys. Lett. 54(26), Jun. 26, 1989, pp. 2634-2636.
Kapon et al., “Chirped Arrays of Diode Lasers for Supermode Control”, Appl. Phys. Lett. 45(3), Aug. 1, 1984, pp. 200-202.
Lindsey et al., “Fundamental Lateral Mode Oscillation Via Gain Tailoring in Broad Area Semiconductor Lasers”, Appl. Phys. Lett. 47
Arroyo Teresa M.
Hanson Loyal McKinley
Leung Quyen Phan
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